1. Field of the Invention
This invention relates to graphics. In particular, the invention relates to graphics and video processing.
2. Description of Related Art
Graphics and video systems are now being used in various platforms that are beyond the traditional applications. There is a growing need for the integration of computer-generated graphics and real-time video images in applications ranging from personal computers (PC), video conferences, to television (TV) set-top boxes. Demands for these high performance graphics and video processing systems have created many design challenges.
In a typical high performance graphics and video systems, there may be different display systems with different display formats. These different display formats may create many incompatibility problems. One problem is the difference in the aspect ratio of the display area. For example, a computer-generated image may look fine on a computer monitor but is distorted when displayed on a TV monitor. In another example, a digital image displayed on one display resolution may look different on another display resolution.
Display on a monitor may also be flickered producing undesirable viewing effects. The flickering may be a result of high frequency update rate of the horizontal lines, or the interlacing of fields in interlaced display mode. To reduce the flickering, traditional methods employ analog techniques using delay elements and switching circuits. These methods are inflexible, unreliable, and tend to be expensive.
Therefore there is a need in the technology to provide an efficient and versatile technique for processing graphical data to correct the aspect ratio and to reduce flickering.
The present invention is a method and apparatus to generate an anti-flickered pixel from a source pixel having a source pixel value in a display memory. The apparatus comprises a plurality of storage elements, a filter, a comparator, and an output selector. The plurality of storage elements store a sequence of pixels in the display memory which includes the source pixel. The filter is coupled to the plurality of storage elements to filter the sequence of pixels. The filter generates a filtered pixel corresponding to the source pixel. The comparator is coupled to the plurality of storage elements to compare the source pixel value with a threshold value. The comparator generates a comparison result. The output selector is coupled to the filter and the storage elements to select one of the source and filtered pixels according to the comparison result. The selected one of the source and filtered pixels is the anti-flickered pixel.